This is the first true macro lens I have owned but I have several other L lenses (500, 400, 300, 200, 70-200, 24-70) and I have to admit that this is the MOST fun lens of them all. The switch positions are absolutely perfect for me unlike some of my other glass. The AF is almost as fast as my 400 which is huge for a macro lens. And the IS...is absolutely quite. So much so that I think its not even on!! Compared to my other L lens IS operation this lens beats them hands down. Tripods can be a total pain in the ass for macro work so having IS is a real bonus. This lens is also sharp wide open and the bokeh is absolutely beautiful. I've not used the non-IS version of this lens but if you are considering which one of these lenses to purchase I would not hestitate to recommend this one for its fast AF, super IS and build quality. My only nit would be that you can't pop the lens cap on or off when the lens hood is on.